Numerical Simulation on Thickness Dependency and Bias Stress Test of Ultrathin IGZO Thin-Film Transistors Via a Solution Process

Abstract

The authors report the effect of ultra-thin channel layer thickness on the performance of an amorphous InGaZnO (a-IGZO) thin-film transistor (TFT). Numerical simulation is used to investigate the thickness effect on the a-IGZO TFT output parameters. The simulation results are compared to measurements of the stability of nitrate ligand-based hexaaqua complexes solution-processed ultrathin a-IGZO transistors a-IGZO. This TFT is also tested under negative illumination bias stress (NIBS) and positive bias stress (PBS). The thinner channel layer is found to have a better performance than the thicker channel layer. The 4nm-thick, ultra-thin a-IGZO TFT exhibits high saturation mobility (7.56cm(2)V(-1)s(-1)), low threshold voltage (2.73V), a small value of sub threshold swing (0.22Vdec(-1)), and a high on/off ratio (1.77x108). It is also noticed that the threshold voltage (V-th) shifts negatively as the thickness increases. The 4nm long channel TFT shows more stability under NIBS and PBS while 16nm have a strong degradation under NIBS and PBS.